<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }

        .box {
            width: 400px;
            height: 100px;
            margin: 0 auto;
            background: #ddd;
            overflow: hidden;
        }

        .box li {
            width: 48px;
            height: 100px;
            background: hotpink;
            float: left;
            list-style-type: none;
            border-right: 2px solid #489131;
            position: relative;
            overflow: hidden;
        }

        .tit {
            width: 48px;
            height: 100px;
            background: #981561;
        }

        .nei {
            width: 200px;
            height: 100px;
            background: #ef3a7f;
            position: absolute;
            left: 48px;
            top: 0;
        }

        .box ul {
            width: 450px;
        }
    </style>
</head>

<body>
    <div class="box">
        <ul>
            <li>
                <div class="tit">标题</div>
                <div class="nei">内容</div>
            </li>
            <li>
                <div class="tit">标题</div>
                <div class="nei">内容</div>
            </li>
            <li>
                <div class="tit">标题</div>
                <div class="nei">内容</div>
            </li>
            <li>
                <div class="tit">标题</div>
                <div class="nei">内容</div>
            </li>
        </ul>
    </div>

    <script src="../js/jquery.js"></script>

    <script>
        $(".box li").on("mouseover", function () {
            $(this).stop(true).animate({
                width: 248
            }).siblings("li").stop(true).animate({
                width: 48
            })
        })
    </script>

</body>

</html>